After a few days without making Gaia's report, I've come back with some improved things. I'm currently at lvl 178.
I have decided for now to leave the Copper and Uranium mines at lvl 15 and start improving the Shipyard to its maximum level in order to be able to start exploration in space as soon as possible, as I am quite behind in that aspect.
Also the Shipyard skills are at lvl 14, also I have improved the Bunker and the Shield Generator.
Regarding the Ship Skills, the Transporter is currently at lvl 10, so is the Explorer.
That's all the report, I'll come back when I have almost everything ready to start exploring and find more planets.